Recovery of pure cyclo-olefins



Aug. 8, 1950 P. H. CARNELL REcovERY oF PURE cYcLoEoLEFINs Filed May 9, 1947 ATTORNEYS Patented Aug. 8,v 1950 RECOVERY OF PURE CYCLO-OLEFINS Paul H. Carnell, Bartlesville, Okla., assignor to Phillips Petroleum Company, a corporation of Delaware Application May 9, 1947, Serial No. 747,109

15 Claims. 1

This invention relates to the recovery of cycloolens. In one embodiment this invention relates to the recovery of a cyclo-olefin from a mixture containing other organic materials. In one specific embodiment this invention relates to the recovery of a low-boiling cycle-olefin, such as cyclo-hexene, from a mixture of hydrocarbons containing the same.

This application is a continuation-in-part of my copending application, Serial No. 671,111, filed June 20, 1946, now Patent 2,498,789, granted February 28, 1950.

Substantially pure cyclo-olefins are becoming more and more important as intermediates in the manufacture of certain chemicals such as cyclic alcohols, aldehydes, and ketones, as well as certain resins, drying oils, and the like. Cycloolefins do not occur assuch in nature; however, they are found as by-products in certain gascracking and oil-cracking operations. They may be made directly by dehydrogenating cycloparafflns, and are also produced by decomposition, at a high temperature, of other hydrocarbons. Usually when cyclo-olefins are made, there are concomitant side reactions forming products which present a problem in recovery and purification of the desired cyclo-olefin due to the similarity of the boiling points, melting points, or chemical characteristics of various hydrocarbons in the mixture. In many cases it is difficult to separate a cyclo-olefin from a corresponding cycloparaffm, and/or other hydrocarbons having closely related boiling points, or from an aliphatic olen, by fractionation.

Separation of a mixture of materials into its component parts by fractionation is usually satisfactory when the boiling points of the components of the mixture are suiiiciently diiferent so that the products may be separated by that method. Sometimes it is desirable to remove one component of a mixture from the mixture; but, due to the similarity of its boiling point With the boiling point of some other component, this cannot be accomplished efciently by fractionation. Also, certain compounds form azeotropes when they are admixed with each other which makes it very difficult or impossible to separate them by fractionation. This is particularly true of compounds found in petroleum and petroleum products. It is necessary in many cases to take advantage of differences in chemical behavior of the individual components of a mixture in order to effect the desired separation of a mixture into'v its component parts or to remove one of the com-- pounds from such a mixture. The separation of a cyclo-olefin from its corresponding cyclopar- 2 afn, and other hydrocarbons, presents such a problem.

I have found that a cyclo-olefin may be removed from a hydrocarbon mixture containing the same by taking advantage of the chemical activity of the cyclo-olefin with hydrogen fluo-v ride, and particularly with aqueous hydrogen fluoride.

An object of this invention is to recover a substantially pure cyclo-olefin from a mixture with other materials. y

Another object of this invention is to recover cyclo-olens from a mixture with other organic compounds.

Still another object is to recover a cyclo-olefin from a hydrocarbon mixture containing the same where the components of such a mixture have approximately the same boiling point as the cyelo-olefin to be recovered.

Another object is to recover cyclohexene from a mixture of hydrocarbons containing the same.

Other objects and advantages of the present invention will become apparent to those skilled in the art from the accompanying disclosure and description.

According to one embodiment of this invention a substantially pure cyclo-olefin is recovered from a mixture of organic material containing the sameby treatment with hydrogen fluoride, and preferably with an aqueous solution of hydrogen fluoride. When an aqueous solution of hydrogen fluoride contacts the mixture of organic material containing a cyclo-olefin, the cyelo-olefin reacts with the hydrogen fluoride contained in the aqueous solution to form a cyclo` alkyl fluoride. The reaction mixture then separates into an organic layer and an aqueous layer. The organic layer containing the cycloalkyl fluorides is recovered from the aqueous layer and is fractionated, preferably under reduced pressure, to remove the cycloalkyl fluoride therefrom. In

this manner the cyclo-olefin is separated from' the organic mixture. Thereafter the cycloalkyl fluoride is heated, either with or without the use of a catalyst, to a temperature suiliciently high to dissociate hydrogen fluoride therefrom. The

cyclo-,olefin so recovered is a substantially pure product, and the hydrogen fluoride may be returned to the process for :re-use.

The reaction between aqueous hydrogen fluoride'and cyclo-olefin present in the organic mixture is accomplished by contacting the organic material in the liquid phase with the Water-hydrogen fluoride mixture in either the liquid or vapor phase at somewhat higher than atmospheric temperature. .This reaction step may be.

action step is preferably effected at a tempera-,

ture between about 100 and about 400 F., de-

pending upon the particular cyclo-olefin involved and generally at suicient pressure to maintain the cyclo-olefin in the liquid state. Suitable conditions in any particular instance can be readil7 found by simple experiments by one skilled in the art in accordance with the present disclosure.

Where it is found particularly suitable, the reaction between the aqueous hydrogen fluoride and the cyclo -olen may be carried out in the liquidvapor phase with comparative ease. at a temperature where one reactant is maintained in vapor phase.

The concentration of the hydrogen fluoride to be 'contacted with the cyclo-olen-hydrocarbon mixture is preferably between and 70 per cent; however, in some cases a lower or higher concentration up to 100 per cent of hydrogen fluoride may be used. In one embodiment small portions of anhydrous hydrogen uoridemay be bled into the reaction chamber containing the cyclo-olefin under such conditions as to effect hydrouorination with a minimum of polymerization. As a rule, however, acid concentrations above 70 per cent produce an undesirable amount of cycloolefin polymer unless the reaction is conducted at low temperatures; acid concentrations below 30 per cent require rather severe reaction conditions for the production of cycloalkyl fluoride. The relative amounts of cyclo-olefin and aqueous hydrogen fluoride are not critical, but the aqueous acid preferably contains hydrogen fluoride in stoichiometric excess of the cyclo-olefin. vThe contact time for the reaction between the cycloolen and the hydrogen fluoride will vary from about l to about 60 minutes or longer. The contact time for such a reaction depends considerably upon the particular cyclo-olefin involved, concentration of hydrogen fluoride and the temperature employed.

The chemical nature of the reaction step of the process in which the cyclo-olen reacts with the hydrogen fluoride constitutes a chemical interaction between the cyclo-olefin itself and the hydrogen fluoride whereby probably the corresponding lcycloalkyl fluoride is formed. At least a molecular equivalent of hydrogen liuoride to cyclo-olefin is used, and preferably the hydrogen fluoride is' in excess of the cyclo-olen present inthe organic mixture.

After the organic fluoride has been formed, the entire organic material is charged preferably to a conventional fractional distillation column, and there under appropriate conditions of temperature and pressure the hydrocarbon material is separated from the cycloalkyl fluoride'. The hydrocarbons are'removed as an overhead fraction from the column and the cycloalkyl iiuoride is removed as a bottom product from the column.

The temperature and pressure of the fractionating step will depend upon the particular hydrocarbon mixture treated as the boiling points of the hydrocarbons vary depending upon the number of carbon atoms per molecule; also the boiling point of the cycloalkyl iiuoride depends-upon the number of carbon atoms in each molecule. lt is preferable, in some cases, to use vacuum distillation in order to prevent the use of a temperature so high as to effect dissociation of the cycloalkyl fluoride during the fractionating step. Temperatures between about 50 and about 180 F., depending upon the cycloalkyl uoride involved, are suitable to make the separation between the hydrocarbon materials and the cycloalkyl fluorides. The cycloalkyl fluorides dissociate into corresponding cyclo-olefins and hydrogen uoride at elevated temperatures; therefore, in some cases there is a maximum temperature to which the cycloalkyl fluoride can be heated and still avoid dissociation.

After the fractionation step where the cycloalkyl fluoride is separated from the organic mixture, the dissociation of the cycloalkyl fluoride to release hydrogen uoride is accomplished by charging the cycloalkyl f uoride preferably to a conventional stripping column under conditions of temperature and pressure necessary to decompose the cycloalkyl fluoride. A catalyst, such as, for example, sulfuric acid or added hydrogen fluoride, may be used, if desired, to catalyze the dissociation of hydrogen fluoride from the cycloalkyl fluoride. The hydrogen fluoride formed by dissociation of cycloalkyl fluoride autocatalyzes further dehydrouorination. The hydrogen fluoride is removed as an overhead fraction from` the stripping column and substantially pure cyclo-olefin is removed from near the bottom of the column.

The temperature cf the stripping step is relatively higher than the temperature of the reaction where the cycloalkyl fluoride was produced. Temperatures between about and about 500 F. `with the corresponding pressure required to maintain the cyclo-olefin in the liquid phase are generally suitable to decompose the cycloalkyl fluoride into cyclo-olefin and hydrogen fluoride and to liberate hydrogen fluoride therefrom. Some of the cycloalkyl fluorides, for example, cyclopentyl and cyclohexyl fluorides, dissociate at a satisfactory rate at their normal boiling point. lit may be preferable to use other temperatures than within this range since ultimately the required temperature for decomposition or stripping depends upon the thermal stability of the cycloalkyl fluoride and the bubble point temperature of the organic mixture in the stripping column.

The process as described in this invention is particularly suited to mixtures in which the hydrocarbons present in addition to the cycloolens are predominantly close-boiling, hydrogen fluoride resistant hydrocarbons such as aromatic compounds, that is, benzene, and/or saturated aliphatic or cyclic compounds, that is, aliphatic hexanes or cyclohexanes. A specific mixture could be one composed of the following compounds:

Boiling point, F.

Cyclohexene 181 Cyclohexane 178 Benzene 176 Treatment of this mixture with aqueous hydrogen fluoride under the conditions described in this invention yields cyclohexyl fluoride, which has a boiling point of about 212 F., unreacted benzene and cyclohexane. The cyclohexyl fluoride is separated from the benzene and cyclohexane by reduced pressure distillation and is then heated to about 212 F. at atmospheric pressure to yield cyclohexene and hydrogen uoride.

Any small amount of cyclo-olefin polymerformed by this process may be heated to give hydrogen fluoride and a high-molecular weight drying oil as taught in my copending application, Serial No. 637,266, filed December 26, 1945, now Patent 2,481,498, granted September 13, 1949.

Also, by this invention a substantially pure cyclo-olefin may be recovered from a mixture comprising a cyclo-olefin and an aliphatic oleiin. This may be accomplished by taking ladvantage of the diilerence in chemical activity of the aliphatic olen and cyclo-olefin toward aqueous hydrogen fluoride.

I have found that a cyclo-olefin, for example, cyclopentene, reacts with aqueous hydrogen 11u0- ride at moderate temperatures to form cyclopentyl fluoride and that straight-chain olefins, for example, pentene-l, do not react to a great extentunder the same conditions. The normal aliphatic olens, as a rule, react with much more diiflculty with aqueous hydrogen fluoride than do cyclo-olens; however, the iso-aliphatic olefins react more nearly like the cyclo-olefins with aqueous hydrogen fluoride than do the normal aliphatic olens. Nevertheless, in some cases cyclo-oleiins may be separated from the iso-aliphatic oleflns by application of this invention.

When aliphatic` olens such as propylene and the butenes are treated with aqueous hydrogen iiuoride at elevated temperatures, the respective alkyl fluorides and alcohols are formed. However, when cyclo-olens such as cyclopentene and cyclohexene are subjected to treatment with aqueous hydrogen fluoride at elevated temperatures, cycloalkyl fluorides are formed which are l not hydrolyzed to alcohols by aqueous hydrogen iluoride. In separating cyclo-olens from aliphatic olens by use of aqueous hydrogen fluoride, in certain cases both types of alkyl fluorides are formed with substantially equal ease; in such cases, advantage may be taken of the fact that an alkyl fluoride hydrolyzes to an alcohol in the presence of aqueous `hydrogen fluoride. The alkyl fluoride may be hydrolyzed to the corresponding alcohol whichl thenmay be separated from the cycloalkyl uoride by fractionation.

The cyclo-olenswhich may be recovered in substantially pure form, from admixtures of hydrocarbons containing the same, by this invention include cyclo-oleflns containing more than four and less than seven carbon atoms in the ring. However, in its broadest embodiments, this invention is not limited to these speciccyclo-olefins but includes separation and recovery of such cyclo-olefins with saturated side chains, and other cyclo-olefins of higher molecular weight, particularly'those having a total of notmore than about ten carbon atoms per molecule.

The accompanying drawing is a diagrammatic illustration of apparatus in which an embodiment of this invention my be carried out. A hydrocarbon mixture containing a cyclo-olefin and other hydrocarbons is passed through line Ill to reactor I2 where it is contacted with aqueous hydrogen uoride. The aqueous hydrogen fluoride is introduced to the reactor through lines I4 and I6. The contact of the acid and hydrocarbon phases within the reactor may be accomplished by iet or mechanical agitation. In cases of multi-stage or packed tower contacting, counter- 'current flow of acid andA hydrocarbonis preferred.

The reaction mixture flows' from reactor I2v through line I8 to separator 20 where phase sepasolutionof organic materials. 'The lower layer,-

which is chiey aqueous hydrogen iiuoride, is recycled through lines 22 and I6 to reactor I2.v` .A portion of this aqueous solution may be lWithdrawn from the system through line 24, if desirable. The upper layer from separator 20 flows through line 26 to vacuum fractionator 28 where cycloalkyl fluoride formed in reactor I2 and any polymer that may be present are separated from unreacted cyclo-olefin and other hydrocarbons that may be present. Unreacted cyclo-olen and other hydrocarbons are recycled from vacuum fractionator 28 through lines 36 and 32 to reactor I2. A portion of the cyclo-olen and other hydrocarbons withdrawn from the vacuum fractionator 28 may be removed from the system through line 34. Cycloalkyl iluoride passes from vacuum fractionator 28 through line 36 to stripper 38 where suflicient heat is supplied to dissociate and strip hydrogen uoride from the cycloalkyl .nuoride. The dissociated hydrogen uoride is recycled from stripper 38 'through lines 40, 42, I 4 and I6 to reactor I2. If desired, a portion of the hydrogen fluoride from stripper 38 may be recycled through lines 40, 42, and 44 to stripper 38 as a reflux and to catalyze the decomposition of the cyclohexyl fluoride. Other catalysts, such as sulfuric acid, as discussed elsewhere herein, may be used in stripper 38. Resulting cyclo-olefinis withdrawn from the bottom of stripper 38 through line 46. Any polymer that is formed in the separation may be withdrawn from vacuum fractionator 28 through lines 48 and 56 and removed from the system, if desired, or passed through lines 48 and 52 to heater 54 where heat is applied to dissociate hydrogen fluoride that may be contained in the polymer, such hydrogen fluoride being recycled from heater 54 through lines 56, 58, 42, I4 and I6 to reactor I2 or withdrawn from .the system through line 60. The dehydro-fluorinated polymer or drying oil is withdrawn from heater 5,4 through line 62. y

Example I An 800 ml. bomb or chamber of Monel metal is charged with 225 gm. of 50 per cent aqueous hydrogen fluoride solution and gm. of a hydrocarbon material containing cycloheXene. The bomb is clamped to a'platform rocker and is fitted with a suitable pressure gauge. The bomb is slowly heated to a temperatureof about 240 F, over a period of about 5I) minutes, during which period the contents of the bomb are agitated by rocking. The maximum pressure in the bomb is about 50 p. s. i, g. The bomb is cooled and the` contents thereof removed. A liquid organic phase from the bomb, which is separated from the liquidwater phase, is fractionated under reduced pres-,

sure, a low-boiling fraction comprising unreacted' cyclohexene is removed as overhead product from the fractionating column and cyclohexyl fluoride is'removed Jfrom the bottom of the still. Cyclo-,- hexene has a boiling point of about 181 F. and cyclohexyl fluoride has a boiling point of about 212 F. The cyclohexyl fluoride product from the' til1ation,-is heated further to liberate any hydro-- gen fluoride? retained.. in it: Theresultingfmaf terialleftafter tl'iel'leating'treatment ofthepoly'- meri-fis aihiglnmolecular Weighttoilfhaving good drying oilpropertiesnseulin paintsiand Var- Iiishes.' wasnot determined, .butit .is highly unsaturated and@v boils above about :194 F.

Exampley I I Aboutofgrams of: aumixture comprising apiproximately 'equimolar proportions of pentene-l.

andV cyclopentenewhich have boilingpoints of aboutzlD/l. and- 113?" F.; respectively; is contacted Withabout 100 `grams of 40 .per cent .aqueouszhyn cyclpentene together with some Water is obtained overhead," After drying by conven-tional'methods, tliey cyclopentene is substantially pure.

Inasmuch as the foregoing description comn prises'preferred'embodiments ofthe invention ity isrtobe understood that the invention should not beunnecessarily limited thereto and that modications andf variations may be made thereinl Withoutdeparting-from the invention or from the` It is understood that the terms'cycloholenwand open chain or aliphaticl are intended to be synonymous vvith scopey of the claims.

olefin cyclic mono-olefin and open chain or aliphatic mono-olefin respectively, as used'in this specication' and'appended claims.

l. A method for the separation of a cyclic monoolen from a mixturel ofstraight chain monoolenhaving-asimilar boiling point assaidfcyclic mono-olefin, which comprises continuously contactingsaid mixture containing saidcyclic lmono-.-

olen with anaqueous solution of4 hydrogen iiuoride; Which4 solution. contains. between.. about. 30. and about .70 Weight per centof hydrogen fluoride, maintaininga temperature` in the range ofbetweenrabout 100. and about 400 F. and vsuilcient pressure-` to maintain substantially liquid phase andA for-aperiod oftime of=betweenabout 1 minute:` andiabout. 60- minutes, vmaintaining. at least a moLratio, ofcyclic mono-olen 4to hydrogen .nuo-.-Y

ride .such @that cycloalkyl fluoride is formed by re-4 action between Isaid cyclic mono-olenand hydrogenviiuoride, separatinga resulting. organic solution-from a resultingaqueous solution, separating.

cycloalkyl .fluoride containedin said organic solutionby fractionation at -atemperature Withinthe rangepbetWeen-about and about180 F., and

dissociating hydrogen fluoride from resulting.

cycloalkyluoride by treating at a` temperatureinthe rangefof between about 200 and 500 F; andl at, suicientpressure .to substantially prevent .the vaporizationot the v.resulting cyclic mono-olen and ,recycling `at least'a portionof the dissociated hydrogen fluoride toc-the process and recoveringv acyclic mono-olefin asa product of the process.

2'.- A method of separating a cyclic mono-olefin from an: aliphatic mono-oleliny havingthe same numbersofrcarbon atoms per molecule which com-l prisescontacting. amixture of saidolens with an aqueous mixture of hydrogenv iluoridejy which Thei exact composition ofthe dryingoil.

mixture containsy 30vto 1 '70 per. cent `by Weight` of hydrogen fluoride at a-temperatureof to 400"v F. whereby a cycloalkyl fluoride is formed and said aliphaticA mono-olefin remainsunreacted,

= separating` a resulting organic solution from a resulting aqueous mixture, separating saidcyclo.- alkyl fluoride from said organic solution by fractionation, removing-iunreacted aliphatic olen as a vlow-boiling fraction; heating aresulting cycloalkyl `fluoride under conditions .such that hydrogeniuoride is dissociated `therefrom and substantially pure'cyclic mono-olen is recovered.

3. A method for the separation of a cyclicv mono-olefin from'a mixture of 'paraiiins and open chain Vmono-oleiins-having substantially the same boiling point as said cyclic mono-olen WhichY comprisescontactingsaid mixture containing said' cyclic mono-olefin having more than four and less` than seven carbon atoms inthe ring` with an aque-ous solution of :hydrogen uoride Whicl'rsolu-- tion contains 30 '50.70 Weightper cent of hydro-Y genfluoridefata temperature of 100 to 400 F. whereby the corresponding cycloalkyl fluoride is formed, separating' a resulting organic solution froma-resulting aqueous mixture, separating resulting cycloalkyl iiuoride from saidorganic solution by fractionation and heating said resulting cycloalkyl fluoride under conditions and in the presence offaicatalyst'such that hydrogen iiuoride is dissociated therefrom, and recovering resultingcyclic mono-olefin as a product' of the process.

41 A method' for the separation of' a cyclic mono-olefin having more than four andA less than seven'carbon atoms in the ring from a mixture comprising paraiiinhydrocarbons having a similar boiling point as said cyclic mono-olefin, w-hich comprises continuously contacting said mixture; of paraffin hydrocarbons containing said cyclic mono-olenA with an; aqueous solution of' hydrogen' fluoride which solution contains betvveenl about'30 and. about 70 Weight per cent of' hydrogen fluoride, maintaining a temperature in the range of between about 100 and about 400 F. and suicient pressure to maintain substantially liquid phase and for a. period of time of between about l minute and about 60 minutes, maintaining at least a.mol ratio of cyclic mono-olen to hydrogenluoride such that cycloalkyl fluoride is formed by reaction. between. said cyclic mono-Y olefin and hydrogen fluoride, separatingv a resulting organicy solution from a resulting aqueous solution, separating cycloalkyl fluoride contained in said. organic solution .by fractionation at atemperaturew-ithin the range of betweenl about.,50. andabout F., and dissociating hy-A drogen .iiuoride from resulting cycloalkyl fluoride by treating said cycloalkyl iiuoride `at aternpera-v ture in therange of between about'200 and 500 F. and-atisucient pressure to substantially prevent. the vaporization of.- the resulting cyclic mono. oleiin and. recycling at leasta-portion of the dis sociated hydrogeny iiuoride to the process and. recovering a cyclicA mono-olefin as arproduct of: the process.`

5.' Aarnethod for thefseparation of-cyclohexene, from a hydrocarbon mixturel comprising openA chain mono-olefins; cycloparaflins and parainsi having. a similar boiling point-ascyclohexene, which.` comprisesf continuouslyy contacting said mixture` containingcyclohexen'e with an aqueous 7 and vsuicientll pressure to maintain substantially liquid phase and'for aperiod of time of between vabout 1`minute and about 60 minuteamaintaining at least a'mol ratio of cyclohexene to hydro'- gen fluoride such that cy'clohexyl fluoride is 1 yformed by reaction between said cyclohexene and rhydrogen fluoride, separating a resulting organic rsolution from a resulting aqueous solution, separating cyclohexyl fluoride contained in said organic solution by fractionation at a temperature Within the range of between about 50 andjabout 180 F., and dissociatinghydrogen fluoride from resulting cyclohexyl fluoridel by treating'saidcy- 'clohexyl fluoride at altemperaturein the range of between about 200'and 500 F. vand at a sufficient pressure tosubstantially prevent the vaporiz'ation ofy the resulting cyclohexeneand'e'- lcycling' at least la portion of the dissociated hyjdroge'n uorideto the processl and recovering" cyclohexene as a product of the process.

a temperature in the range of between about 100 and about 400 F. and suilcient pressure tornaintain substantially liquid phase and fora period vof time of between about 1 minute and about 60 minutes, maintaining at least a mol ratio of cyclopentene to hydrogen fluoride such that cyclopentyl fluoride is formed by reaction between said cyclopentene and hydrogen fluoride, separating a resulting organic solution from a resulting aqueous solution, separating cyclopentyl fluoride contained in said organic solution yby fractionation at a temperature within the range of vbetween about 50 and about 180 F., and dissociating hydrogen fluoride from resulting cyclopentyl fluoride by treating at a temperature in the range of between about 200 and 500 F. and at sufficient pressure to substantially prevent the Vaporization of the resulting cyclopentene and recycling the dissociated hydrogen fluoride to the process and recovering cyclopentene as a product of the process.

'1. A method for the separation of cyclopentene from a mixture comprising pentene-l and cyclopentene, which comprises continuously contacting said mixture with an aqueous solution of hydrogen fluoride which solution contains between about 30 and about 70 weight per cent of hydrogen fluoride, maintaining a temperature in the range of between about 100 and about 400 F. and sufficient pressure to maintain substantially liquid phase and for a period of time of between about 1 minute and about 60 minutes, maintaining at least a mol ratio of cyclopentene to hydrogen fluoride such that cyclopentyl iiuoride is formed by reaction between said cyclopentene and hydrogen fluoride, separating a resulting organic solution from a resulting aqueous solution, separating cyclopentyl iluoride contained in. said organic solution by fractionation at a temperature within the range of between about 50 and about 180 F., and dissociating hydrogen fluoride from resulting cyclopentyl fluoride by treating said cyclopentyl fluoride at a temperature in the range of between about 200 and 500 F. and at suficient pressure to substantially prevent the vaporization of the resulting cyclopentene and recycling at least'a portion of the dissociated hydrogeniiuoride to the process'and recovering cyclopentene as a product of the process.

8. A method for the separation of cyclohexene from a mixture comprising cyclohexene, cyclohexane and benzene, which comprises'continuously contacting said mixture with an aqueous solution of hydrogen r'fluoride which solution contains between about 30 and about 70 weight per cent of hydrogen fluoride, maintaining a temperature in the range of between about and about l400" F, and sucient pressure to maintainy substantially liquid phase and for a period of time of between about 1 minute and about 60 minutes, maintaining at least a mol ratio of cycloh'exene to hydrogen fluoride such that cyclohexyl fluoride is formed by reaction between said cyclohexene and hydrogen fluoride, separating a resultingorlgarlic solution from a resulting aqueous solution.,

separating cyclohexyl fluoride contained in said organic solutionl by fractionation ata temperature within the range of between about 50 and about F., and dissociating hydrogen fluoride 'from resulting cyclohexyl fluoride by treating said cyclohexyl fluoride at a temperature in `the rangeV of between about 200V and 500 F.

and at sufficient pressure to substantially prevent the vaporization of the resulting cyclohexene and recycling at least a portion of the dissociated hydrogen fluoride to the process and recovering cyclohexene as a product of the process.

` 9. A method for the separation of a cyclic mono-olen from a mixture comprising Said cyclic mono-olefin and open chain mono-olens having substantially the same boiling point as said cyclic mono-olefin, which comprises contacting sucha mixture containing a cyclic mono-olefin having more than 4 and less than 7 carbon yatoms in the ring withan aqueous solution of hydrogen fluoride, which solution contains between 30 and 70 weight per cent of hydrogen fluoride, at a temperature in the range of 100 to 400 F. whereby the corresponding cycloalkyl fluoride is formed, separating a resulting organic solution from a resulting aqueous mixture, separating a resulting cycloalkyl fluoride from said organic solution by fractional distillation, heating said resulting cycloalkyl fluoride under conditions such that hydrogen fluoride is dissociated therefrom, and recovering the resulting cyclic mono-olefin as a product of the process,

10. The method of claim 9 in which said cyclic mono-olefin is cyclohexene.

11. The method of claim 9 in which said cyclic mono-olen is cyclopentene.

12. The method of claim 9 in which said cyclic mono-olefin has not more than ten carbon atoms per molecule.

13. A method for the separation of cyclohexene from a mixture comprising oyclohexene and benzene, which comprises continuously contacting said mixture with an aqueous solution of hydrogen fluoride which solution contains between 30 and '70 weight per cent of hydrogen fluoride, maintaining a temperature in the range of between 100 and 400 F. and sufficient pressure to maintain substantially liquid phase and for a period of time of between l minute and 60 minutes, maintaining at least a mol ratio of cyclohexene to hydrogen fluoride such that cyclohexyl fluoride is formed by reaction between said cyclohexene and hydrogen iluoride, separating a resulting organic solution from a resulting aqueous solution, separating cyclohexyl fluoride contained inA said organic solution by fractionation at a temiperature within .the range of betWeen.50and.-.180 JF., and dissociating hydrogen iluoride :from .re-

sulting cyolohexykfluoride bytreatingfsaidlcyclo- .Lhexylfluoride atia temperature inthe ,range of between-200 and. 500 F. andat suicient pressure .tosubstantially prevent the'vaporization of the Lresulting-oyclohexene, and recyclingzat least a por- .tion ,of the .dissociated hydrogen luorideftothe .',processand recovering cyclohexeneas a product ofuthe.-.process.

.114. .A method for the. separation ofcyclohexene .froma mixture comprising eyclohexeneand cyclofhexane,-.1which comprises continuously contacting saidf mixture withtan aqueous: solution of hydro- `gen Lfluor-ide Wh-ich 4-solutioni contains between 30 .and `70 weight per cent .of :hydrogen uoride, maintaining -atemperature inthe range'ofloetween v100 V.and A400" and-sufcient pressure .to maintain .substantially .liquid phase .and for -a 1period ofltimeof between 1. minute .and.60.rnin `utes,maintaining at least a mol ratio ofcyclo- :hexene to. hydrogeniluoride such that cyclohexyl .fluoride -is-formed by reaction betweenlsaid cyclohexeneand hydrogen uoride, separating are- .sultingorganic solution from a resulting aqueous .solutiomseparating cyclohexyluoride contained insaid organic solution by fractionation. at a tem- .,perature within the range of between 50 and 180 F., .and rdissociating hydrogen uoride .from resultingcyclohexyl iluorideV by treatingsaid cyclohexyl .fluoride at .-a .temperaturein the range .of .between 200 and .500..F. and atsufcientpressure tosbstantially preventthe vaporization of the resulting `cyclohexene .and recycling at 'least a ,portion of the. dissociated hydrogenluoride to the process and recovering cyclohexene as a product of. the` process.

I5. A method for the separation of cyclopentene froma mixture comprising a straight chain pen- '..tene andcyclopentene, which comprises continuously'contactngsaid mixture with an 'aqueous solution of hydrogen. iiuori'de whichsolution containsbetween `30:and 70 .Weightper cent of' hy- `.dlQ'.genqfluoridegmaintaining fa temperat11re in-.the

frangexoi :between 100 :and 400 2F. andfsufficient v.pressure to :maintain .substantially .liquid vphase I.an'diorza .period .ofi time. of :between :.1A minute and .60 minutesy maintaining at least. a -mol z ratio fof cyclopentene .to hydrogenV iiuoride such that lcyclo- -pentylfluorideis formed by reaction-betweensaid .cyclopentene and-.hydrogen viiuoride, separating-a .resulting organic #solution from a resulting-aqueous solution, .separating cyclopentyl `uoride con- A'tained .in said `organic solution by4 fractionation ata temperature within the range .of between .and .180 F., and .dissociating hydrogen fluoride .from resulting cyclopentyl uoride by treating .said cyclopentylv fluoride. at'zaf-temperature ,inf the `rangeof-between2001-and 500 Rand at sufcient pressure.tofsubstantally prevent the nvaporization .of lthe y.resulting cyclopentene vand recycling I.at vleastaportion-.of theV dissociated hydrogen uoride to the process and .recovering .cyclopentene .-asya. product ofthe: process.

.PAUL H. ACARNELL.

" REFERENCES .CITED .The A following references are of record inn-the le .ofthis patent:

"A UNITED vSTATES PATENTS Number Name .'Date .2,220,173 'fGrosse et jal. `.`.Nov.`5,.1`940 236.8;44'6 .v Buc. .Jan. .30,194'5 "2,386,333 .Morris .Oct..`9, 1945 12,386,334 'Morris Oct.9,A1945 ""Society, vol."66 -(1944i) pages 1759-64. 

1. A METHOD FOR THE SEPARATION OF A CYCLIC MONOOLEFIN FROM A MIXTURE OF STRAIGHT CHAIN MONOOLEFIN HAVING A SIMILAR BOILING POINT AS SAID CYCLIC MON-OLEFIN, WHICH COMPRISES CONTINUOUSLY CONTACTING SAID MIXTURE CONTAINING SAID CLYCLIC MONOOLEFIN WITH AN AQUEOUS SOLUTION OF HYDROGEN FLUORIDE WHICH SOLUTION CONTAINS BETWEEN ABOUT 30 AND ABOUT 70 WEIGHT PER CENT OF HYDROGEN FLUORIDE, MAINTAINING A TEMPERATURE IN THE RANGE OF BE TWEEN ABOUT 100 AND ABOUT 400*F. AND SUFFICIENT PRESSURE TO MAINTAIN SUBSTANTIALLY LIQUID PHASE AND FOR A PERIOD OF TIME OF BETWEEN ABOUT 1 MINUTE AND ABOUT 60 MINUTES, MAINTAINING AT LEAST A MOL RATIO OF CYCLIC MON-OLEFIN TO HYDROGEN FLUORIDE SUCH THAT CYCLOALKYL FLUORIDE IS FORMED BY REACTION BETWEEN SAID CLYCLIC MONO-OLEFIN AND HYDROGEN FLUORIDE, SEPARATING A RESULTING ORGANIC SOLUTION FROM A RESULTING AQUEOUS SOLUTION, SEPARATING CLYCLOALKYL FUORIDE CONTAINED IN SAID ORGANIC SOLUTION BY FRACTIONATION AT A TEMPERATURE WITHIN THE RANGE OF BETWEEN ABOUT 50 AND ABOUT 180*F., AND DISSOCIATING HYDROGEN FLUORIDE FROM RESULTING CYCLOALKYL FLUORIDE BY TREATING AT A TEMPERATURE IN THE RANGE OF BETWEEN ABOUT 200 AND 500*F. AND AT SUFFICIENT PRESSURE TO SUBSTANTIALLY PREVENT THE VAPORIZATION OF THE RESULTING CYCLIC MONO-OLEFIN AND RECYCLING AT LEAST A PORTION OF THE DISSOCIATED HYDROGEN FLUORIDE TO THE PROCESS AND RECOVERING A CYCLIC MONO-OLEFIN AS A PRODUCT OF THE PROCESS. 